Fabrics, including both woven webs and nonwoven webs, and their manufacture have been the subject of extensive development resulting in a wide variety of materials for numerous applications. There have also been developed different ways and equipments to make fibrous webs having desired structures and compositions suitable for these uses. However, it is not always possible to efficiently produce a fibrous web having all the desired properties as formed, and it is frequently necessary to treat the fibrous web to improve or alter one or more properties. For instance, many fibrous webs have a limited ability to absorb water or water vapor.
Hydrogel polymers are known for their effective heat transfer properties as well as their adhesive properties. As such, hydrogels have been used as a component in various pads used for heating or cooling patients whose body temperature needs to be controlled by external means. The hydrogel polymer is used in a layer in direct contact with the skin of the patient. Desirably, the skin-contacting layer will provide good adhesion of the pad to the skin, provide good structural integrity, minimize adverse effects on the skin, and provide efficient heat transfer.
Additionally, the hydrogel layer remains a significant portion of the cost of temperature control pads, which pads are generally discarded after use by a single patient. Thus, there remains a need for new low-cost hydrogel layers for use in temperature control pads and other heat transfer devices.